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Biomedical subjects

D König

Publications and source records attributed to D König.

17 recordsLinked to original sources
PubMed1998

Free plasma catecholamines in spinal cord injured persons with different injury levels at rest and during exercise.

Spinal cord lesion leads to an interruption of pathways from brain to the peripheral sympathetic nervous system, which results in pathological changes in sympathetic innervation. Free epinephrine (E), norepinephrine (NE) and dopamine (DA) were measured in 30 tetraplegics (TETRA), 15 high-lesion paraplegics (T1 and T4, HPARA), 15 paraplegics with injuries between T5 and T10 (MPARA), 15 low-lesion paraplegics (below T10, LPARA) and 16 non-handicapped control persons (C) at rest, at 60 and 100% of maximal oxygen consumption during graded wheelchair ergometry (WCE). The TETRA showed significant lower E and NE levels at rest and only slight increases during physical exercise. The E and NE concentrations of the paraplegics with a lesion below T5 were significantly higher than those of the high-lesion paraplegics, as well as those of the control persons at every point in the study. All paraplegics and the control persons showed, at submaximal and maximal exercise, a significant increase in NE. Only a slight increase in E in HAPRA was shown. No differences were found at rest and during exercise in E and NE levels in the MPARA and LPARA. No significant differences were found in the dopamine concentration at rest or during exercise for any of the groups. In summary, different levels of lesion and the resulting interruption to sympathetic pathways in the spinal cord are decisive factors in the degree of impairment of sympathetic innervation in SCI persons. Tetraplegics show less preganglionic resting activity because of interruption of impulses from central centers and no considerable stimulation of the sympathetic nervous system during maximal exercise. Individuals with high paraplegia have a partial impairment of catecholamine release, especially of epinephrine, at rest and during exercise. Paraplegics with a lesion level below T5 showed an augmented basal and exercise-induced upper spinal thoracic sympathetic activity in comparison to control persons.

Adult↗
PubMed1998

Zinc, iron, and magnesium status in athletes--influence on the regulation of exercise-induced stress and immune function.

Intense physical exercise has been shown to be associated with immunosuppression and increased rate of infection. The immunosuppressive effect of exhaustive exercise has been attributed to a reduced helper/suppressor T-cell ratio, low salivary levels of immunoglobulin-A, decreased lymphocyte proliferative response and natural killer cell activity, and elevation of stress hormones. Yet some athletes can withstand intense training periods without health problems while others are prone to infections. Thus it has been postulated that other factors may interfere with immunoregulation. The notion that macro- and micronutrients are involved in the regulation of immunological processes and the ability to cope with muscular and systemic exercise stress has been gaining attention. Particularly trace elements have been shown to be related to cell mediated and humoral immunity such as NK-cell activity, T- and B-cell functions, and cytokine release. Many investigations have reported decreased concentrations of trace elements in blood and tissues after training and competition. However, the magnitude of losses is highly dependent on the type and intensity of exercise, the individual regulatory state, and most important, nutrition. This paper reviews the data on zinc, iron, and magnesium status in athletes and summarizes the consequences of deficiencies in these trace elements regarding exercise tolerance and immune function. These elements were chosen since there is evidence they are related to exercise-induced stress and immune function.

Animals↗
PubMed1997

Relationship of serum ferritin concentrations with metabolic cardiovascular risk factors in men without evidence for coronary artery disease.

Elevated serum ferritin concentrations between 200 and 500 microg/l have been found to be a strong risk factor for acute myocardial infarction in Finnish men, but the reason for this association is still uncertain. In the Finnish population ferritin concentrations correlated with factors of insulin resistance syndrome. As these factors have been found to be associated with an LDL subfraction phenotype of increased concentrations of small, dense LDL particles, we hypothesized an association between ferritin and an atherogenic LDL subfraction profile, a finding which could be an explanation for the observed relationship between ferritin and atherosclerosis. Therefore we determined serum ferritin levels, metabolic cardiovascular risk factors, and the LDL subfraction phenotype in 93 healthy men without signs for infection or coronary heart disease. We found that men with moderately elevated ferritin levels (200-500 microg/l; n = 31) had a significantly worse coronary risk profile than men with lower levels ( < 200 microg/l; n = 62). Elevated ferritin concentrations were associated with significantly higher values for serum triglycerides, VLDL cholesterol, VLDL apolipoprotein B (P < 0.01), IDL cholesterol, fasting glucose (P < 0.05) and uric acid (P < 0.01), and lower levels for HDL2b and HDL2a cholesterol and apolipoprotein A-I (P < 0.05), and lipoprotein(a) (P < 0.01). Elevated ferritin levels were, however, not associated with an unfavourable LDL subfraction profile of increased concentrations of small, dense LDL particles.

Adult↗
PubMed1997

[Rationale for a specific diet from the viewpoint of sports medicine and sports orthopedics. Relation to stress reaction and regeneration].

The relation between nutrition and sport has been studied extensively during recent decades. Nevertheless, research interest was focused mainly on the role of dietary macro- and micronutrients as ergogenic aids. Today, there is increasing support for the hypothesis that the nutrient status also has relevance for the prevention and rehabilitation of systemic and muscular stress induced by intense physical exercise. The increase in muscular stress is indicated by the rise in creatine kinase and myoglobin; the systemic stress is associated with characteristic immunological and hormonal changes and an acute-phase response. During and following exercise, the course of cytokines (especially interleukin 6) and acute-phase proteins (C-reactive protein, fibrinogen) as well as cortisol levels are an indirect measure of the exercise intensity and the individual ability to cope with physical stress. It has been shown that the dietary intake and, consequently, the systemic or intracellular concentrations of minerals such as magnesium and zinc, vitamins with antioxidant capacity (vitamin E, C, E, and beta carotine), and the composition of fatty acids can be related to the exercise-induced stress response. Therefore, this review deals specifically with the impact of these nutritional components on the reduction of sports specific muscular damage and systemic stress, especially under the aspect of increased losses during and following intense physical exercise.

Antioxidants↗
PubMed1997

Differences in the concentration and composition of low-density lipoprotein subfraction particles between sedentary and trained hypercholesterolemic men.

There is evidence that a low-density lipoprotein (LDL) subfraction profile of increased concentrations of small, dense LDL particles is less common among trained than among sedentary normocholesterolemic men, but it is still uncertain whether there is a similar association in hypercholesterolemia also. Therefore, we determined the lipid and apolipoprotein concentration and composition of six LDL subfractions (density gradient ultracentrifugation) in 20 physically fit, regularly exercising (>three times per week) hypercholesterolemic men and 20 sedentary hypercholesterolemic controls. Trained (maximal oxygen consumption [VO2max], 57.3 +/- 7.4 mL/kg/min) and sedentary (VO2max, 37.5 +/- 8.8 mL/kg/min) individuals (aged 35 +/- 11 years; body mass index [BMI], 23.9 +/- 2.7 kg/m2) were matched for LDL apolipoprotein (apo) B levels (108 +/- 23 and 112 +/- 36 mg/dL, respectively). Trained subjects had significantly lower serum triglyceride (P < .05) and very-low-density lipoprotein (VLDL) cholesterol levels (P < .05) and higher high-density lipoprotein 2 (HDL2) cholesterol levels (P < .01) than sedentary controls. LDL particle distribution showed that trained individuals had significantly less small, dense LDL (d = 1.040 to 1.063 g/mL) and more large LDL (d = 1.019 to 1.037 g/mL) subfraction particles than sedentary controls, despite equal total LDL particle number. Analysis of LDL composition showed that LDL particles of hypercholesterolemic trained men had a higher free cholesterol content than LDL of untrained hypercholesterolemic men. Small, dense LDL in hypercholesterolemic trained men were richer in phospholipids than those in sedentary controls. These data demonstrate the significant influence of aerobic fitness on lipoprotein subfraction concentration and composition, thereby emphasizing the role of exercise in the treatment and risk reduction of hypercholesterolemia.

Centrifugation, Density Gradient↗
PubMed1997

Effect of exhaustive exercise stress on the cytokine response.

Fifteen athletes were investigated 24 h before, 1 h after, and 20 h after an exhaustive exercise stress test (mean duration 68 min). Testing for cytokines was done in serum, urine, and the supernatants of whole blood cell cultures, which were stimulated with lipopolysaccharide (LPS), concanavalin A (Con A), or phythaemagglutinin (PHA). Elevated levels of interleukin 6 (IL-6) and soluble IL-2 receptor (sIL-2R) were found 1 h after the run in both serum and urine samples. TNF-alpha in serum was also increased, whereas IL-2 in urine was decreased after the exercise. All other testings in serum and urine (including IFN-gamma) gave borderline or negative results. In cell cultures, the LPS-induced release of the inflammatory cytokines TNF-alpha, IL-1, and IL-6 was suppressed 1 h after exercise. Also, the Con-A-induced and LPS-induced release of IFN-gamma, and the PHA-induced release of IL-2 were suppressed 1 h after exercise. In contrast, Con-A-induced release of IL-2 was mildly increased after the run. We conclude that exercise of the intensity and duration described here causes an activation of the immune system, which is immediately counter-regulated. Twenty hours after the exercise, most of the observed changes were back to pre-exercise levels, indicating only a short duration for this suppressive counter-regulation.

Adult↗
PubMed1997

A three-dimensional dynamic simulation model of epithelial tissue renewal.

OBJECTIVE: Based on the study of existing simulation and mathematical models, a dynamic simulation and three-dimensional (3-D) visualization model of the normal and pathologic architecture of the nasal epithelium is proposed. STUDY DESIGN: Positions, sizes, shapes and orientations of the nuclei, basal lamina and lumen were used for 3-D representation of the epithelium. Static modeling was applied to simulate the normal, metaplastic and dysplastic stages of the nasal epithelium. Then, dynamic modeling, starting from a static representation of a normal or a pathologic stage, used the starting values of cell proliferation parameters to simulate a tissue growth process. The basic hypothesis is that consecutive transformations through stages are mainly due to increased cell growth. RESULTS: Normal tissue renewal and progressive transitions between normality and hyperplasia after exposure to formaldehyde were obtained. CONCLUSION: A model that allows study of the evolution of the 3-D tissue architecture during the preneoplastic process in external epithelium is now available. Improvement of the model, consisting of adding information concerning cell communication, extracellular matrix and cell cycle modeling, should help to formulate and sharpen hypotheses concerning structural and kinetic dynamics of this tissue during the preneoplastic process.

Epithelial Cells↗
PubMed1997

Essential fatty acids, immune function, and exercise.

The immunologic response to exercise comprises numerous alterations within the immune system, but how these processes are regulated is still largely unknown. Exercise-related immunological changes include signs of inflammation, such as release of inflammatory mediators, activation of various white blood cell lines and complement, and induction of acute phase proteins. Nevertheless, signs of immunosuppression, such as decreased T and B cell function or impaired cytotoxic or phagocytic activity, can also be observed. Some data suggest that essential fatty acids help regulate inflammatory processes, modulating both cytokine release and the acute phase response. Positive effects of changing dietary essential fatty acids have been demonstrated in chronic inflammatory diseases. In contrast, little is known about the contribution of fatty acids to the exercise-induced immunologic reaction. Essential fatty acids may determine alterations within the immune system following exercise. Therefore, future studies are necessary to evaluate the influence of the fatty acid composition on the inflammatory or immunosuppressive component following heavy exertion.

Acute-Phase Reaction↗
PubMed1996

Assessment of left ventricular dimensions and functions in athletes and sedentary subjects at rest and during exercise using echocardiography, Doppler sonography and radionuclide ventriculography.

During recent years the echocardiographic procedure has been extended regarding the evaluation of left ventricular myocardial function during exertion. During exercise echocardiography, body position is important for the correct assessment of cardiac dimensions and function, particularly for the measurement of the cross-sectional diameters of the left ventricle and diastolic myocardial function. Reliable parameters of left ventricular function during exercise are left ventricular ejection fraction and endsystolic left ventricular volume, but not enddiastolic left ventricular volume. The increase of left ventricular ejection fraction during exercise up to submaximal exertion primarily results in a reduction of endsystolic left ventricular volume and partially in a simultaneous increase of enddiastolic left ventricular volume. In several cross-sectional studies comparing untrained and endurance trained hearts a higher diastolic filling rate, a higher maximal blood flow velocity of early diastolic passive left ventricular filling and a higher early diastolic filling fraction at rest and during exercise could be proved in endurance trained hearts. These training-induced adaptations of diastolic left ventricular function have been confirmed by a longitudinal study with primarily untrained young and older healthy subjects performing a heart rate controlled endurance training programme. Stress echocardiographic and simultaneous spiroergometric investigations indicated a correlation between the diastolic left ventricular function and the maximal oxygen uptake. The currently available data on the sensitivity, the intraobserver and interobserver variability of Doppler echocardiography have shown that this non-invasive procedure is valid for the evaluation of the systolic and the diastolic myocardial function at rest and during exercise. However, the procedure is limited to patients where the ultrasonographic assessment of cardiac structures is not considerably restricted. Furthermore, the reliability of stress Doppler echocardiography is dependent considerably on the practical skills of the observer.

Adaptation, Physiological↗
PubMed1996

Lipoprotein(a) in endurance athletes, power athletes, and sedentary controls.

Elevated concentrations of lipoprotein(a) [Lp(a)] have been shown to be an independent risk factor for atherosclerotic disease. Physical activity and physical fitness have been shown to improve lipoprotein metabolism and reduce the risk of coronary artery disease. Studies on the influence of physical activity and physical fitness on Lp(a) levels including a large number of endurance as well as power athletes have not been performed before. Therefore, we determined parameters of physical fitness (maximal oxygen consumption), physical activity, and lipoproteins in 105 endurance athletes, 57 power athletes, and 87 sedentary young men. As expected, we found that endurance athletes with a good physical fitness had significantly higher concentrations of high-density lipoprotein cholesterol than power athletes and sedentary controls. Regarding mean Lp(a) levels (rocket immunoelectrophoresis), however, there were no significant differences between endurance athletes, power athletes, and sedentary controls. Even when including only those with Lp(a) values > 10 mg.dl-1, no differences were observed between the groups. These findings indicate that intensive training over years and good aerobic fitness improve the ratio of low-density lipoprotein to high-density lipoprotein cholesterol but have no or only minor effects on Lp(a) concentrations.

Adult↗
PubMed1996

Effect of physical exercise and vitamin C on absorption of ferric sodium citrate.

The effect of physical exercise and vitamin C on iron absorption after oral iron administration was investigated. Eight healthy male subjects without iron deficiency were studied after administration of 100 mg ferric sodium citrate complex, 100 mg ferric sodium citrate complex with 200 mg ascorbic acid, and without iron intake, both under resting conditions and after a 1-h bicycle ergometer test at moderate exercise. Serum concentrations for iron, transferrin, and ferritin were measured before and 30 min, and 1, 2, and 4 h after each administration. Under resting conditions administration of 100 mg ferric sodium citrate led to a significant increase in serum iron concentrations. When ferric sodium citrate was administered with vitamin C, iron values increased significantly further. Ingestion of iron together with physical exercise resulted in a higher serum iron concentration than under resting conditions. The maximum increase, reached after 4 h, was 48.2% with exercise and 8.3% without. In combination with exercise, the addition of 200 mg vitamin C did not further increase serum iron concentration. In conclusion, 1 h of moderate exercise enhanced the rate of iron absorption. Under resting conditions the combination of ferric sodium citrate with vitamin C led to significantly increased postabsorption serum iron concentrations compared with iron administration without vitamin C.

Adult↗
PubMed1995

Relationship between obesity and concentration and composition of low-density lipoprotein subfractions in normoinsulinemic men.

Obesity, insulin resistance (IR) with hyperinsulinemia, and a dyslipoproteinemia characterized by reduced high-density lipoprotein 2 (HDL2) cholesterol and elevated levels of small, dense low-density lipoprotein (LDL) particles are risk factors for coronary artery disease (CAD). The impact of obesity independent of hyperinsulinemia on the concentration and composition of small, dense LDL subfractions is uncertain. The aim of this study was to investigate the relationship between obesity indices, namely body mass index (BMI), skinfold measurements (SF), and waist to hip ratio (WHR), and LDL-subfraction particle concentration and composition in 200 healthy men without evidence of IR. A precise analysis of the concentration of lipids and apolipoproteins and the composition of very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and two HDL- and six LDL-subfraction particles was obtained using the technique of density-gradient ultracentrifugation. Dividing the individuals according to BMI showed that those with a BMI greater than 27 kg/m2 had significantly lower HDL2 cholesterol and apolipoprotein (apo) A-I and higher VLDL and IDL cholesterol and apo B concentrations than those with a BMI less than 25 kg/m2. Regarding LDL particles, we found that men with a BMI above 25 kg/m2 had significantly more small, dense LDL particles (d 1.044 to 1.063 g/mL) and correspondingly fewer medium, dense LDL particles (d 1.031 to 1.037 g/mL) than leaner men; those with a BMI above 27 kg/m2 had the highest concentration of circulating small, dense LDL particles. These findings were not influenced by fasting insulin concentrations, IR, or WHR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Compartment pressures after closed tibial shaft fracture. Their relation to functional outcome.

We measured pressures in the anterior and deep posterior compartments continuously for up to 72 hours in 20 patients with closed fractures of the tibial shaft treated primarily in plaster casts. All were examined independently after periods of three to 14 months. Pressures above 40 mmHg occurred in seven (35%) and above 30 mmHg in 14 (70%). No patient had the symptoms of compartment syndrome during monitoring. Abnormalities at review did not correlate with the maximum consecutive time periods during which the compartment pressures were raised. Thus, in the absence of symptoms the monitored pressures did not relate to outcome. Routine monitoring in this type of patient is therefore of doubtful benefit.

Adolescent↗
PubMed1991

Modelling and analysis of 3-D arrangements of particles by point processes with examples of application to biological data obtained by confocal scanning light microscopy.

Within the concept of point processes, a review is presented of quantities which can be used in studies of three-dimensional (3-D) aggregates of particles. Suitable characteristics and estimators are given for both unmarked and marked point processes. To demonstrate the feasibility of such quantitative approaches, an application in histology, dealing with 3-D arrangements of cell nuclei in rat liver, is described. Using a confocal scanning light microscope, 3-D images are recorded and image analysis used to obtain the coordinates of the centroid, together with the volume and DNA content, of each cell nucleus. Examples of results are given, using both unmarked and marked point processes. In the latter case, cell type, nuclear volume and ploidy group are suitable marks.

Animals↗
PubMed1985

The pair correlation function for point and fibre systems and its stereological determination by planar sections.

Traditional stereology consists nearly completely in the determination of particle size distributions and mean values such as Vv and Sv. However, for the description of the 'inner' structure of random structures second-order characteristics such as the pair correlation function or reduced second moment function are useful. In the present paper stereological estimation of second-order quantities for centres of random sphere systems and for random fibre systems are considered. In the case of sphere systems stereological formulae are given which connect the pair correlation function of the sphere centres with quantities available from planar, linear and thin sections. For random fibre systems some exact and approximate stereological methods are suggested which enable the determination of second-order quantities from planar and thin intersections.

Capillaries↗